Acta Cryst. (2002). B58, 109-115 [ doi:10.1107/S0108768101016548 ]
Abstract: The NNO2 group of the title compound is significantly less twisted with respect to the aromatic ring in comparison to a typical secondary nitramine. The amide nitrogen is trigonally hybridized. The nitramino group is almost planar. The C-C-N-N torsion angles vary between ca 13 and 42°, whereas the twist along the N-N bond is much smaller and amounts to between ca 1 and 15°. Those twist angles are governed by a crystal packing and are much larger in the case of crystals of pure N,4-dinitroaniline in comparison to that of its complex with sulfolane. The deviations of the internal angles of the aromatic ring from 120° do not exceed 3°. The presence of the nitro group increases the C-C-C valence angle of ca 2.0-2.6°, whereas an analogous effect associated with the nitramino group is much smaller (ca 0.3-1.3°), pointing to its weak electron-withdrawing properties. The nitramino group displays no tendency to conjugate with an electron-demanding substituent across the ring. It participates in hydrogen bonding only as a hydrogen-bonding donor. It does not act as a proton acceptor, despite the fact that nitramine rearrangement is catalysed by acids.
Keywords: proton donor-acceptor; primary nitramine; twist angles; hydrogen bonding.
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| Structure factor file (CIF format) (205.8 kbytes) |
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